Abstract

A primary aim of the development of an acid drainage treatment plant at Mt Lyell is thepartial to complete rehabilitation of aquatic ecosystems in the lower King River(downstream of the junction with the Queen River) and upper Macquarie Harbour. Anumber of primary environmental remediation targets have been identified for thissystem. These include partial or complete recovery of macroinvertebrate and fishcommunities in the lower King River, partial or complete recovery of native fishrecruitment into tributaries of the lower King River, no mortality or inhibition of growthof salmonids in aquacultural operations in northern Macquarie Harbour.

A suite of toxicological tests were conducted to assess the relative success of three maintreatment options for wastewaters from the proposed treatment plant at achieving theproposed remediation targets. Three 'test waters' were prepared from acid mine drainage(AMD) waters collected from the Mt Lyell lease. They were: pH 3.6 with sulphidisation(to simulate Cu removal by sulphide generating bacteria), pH 7.5 and pH 6.3. The lattertwo test waters were prepared by neutralisation of AMD with quicklime, followed byseparation of supernatant from precipitates. The pH 3.6 test water was produced bypartial neutralisation with limestone slurry, treatment of supernatant with sodiumhydrogen sulphide and separation of supernatant.